• Journal of Environmental Science International
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• v.11 no.2
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• pp.111-120
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• 2002

Asian dust(or yellow sand) occurs mainly in spring and occasionally in winter in east Asia, when the weather conditions are under an upper trough/cut-off low and surface high/low pressure system during blocking episode days associated with the stationary patterns of the upper level jet stream. The transport mechanism for Asian dust during the blocking episode days in spring 2001 was analyzed using the TOMS aerosol index and meteorological mesoscale model 5(MM5). Based on the E vector, an extension of an Eliassen-Palm flux, the blocking episode days were found to be associated with the development of an upper cut-off low and surface cyclones. Concurrently, the occurrence of dust storms was also determined by strong cold advection at the rear of a jet streak, which exhibited a maximum wind speed within the upper jet stream. As such, the transport mechanism for Asian dust from China was due to advection of the isentropic potential vorticity(IPV) and isentropic surfaces associated with tropopause folding. The transport heights for Asian dust during the blocking episode days were found to be associated with the distribution of the isentropes below the IPV At the same time, lee waves propagated by topography affected the downward motion and blocking of Asian dust in China. The Asian dust transported from the dust source regions was deposited by fallout and rain-out with a reinforcing frontogenesis within a surface cyclone, as determined from satellite images using TOMS and GMS5. Accordingly, these results emphasize the importance of forecasting jet streaks, the IPV, and isentropes with geopotential heights in east Asia.

• Proceedings of the Korea Water Resources Association Conference
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• 2002.05a
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• pp.3-16
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• 2002

This article describes some of the recent and on-going research developments of the author at Colorado State University. Advances in the field of sedimentation and river mechanics include basic research and computer modeling on several topics. Only a few selected topics are considered here: (1) analytical determination of velocity profiles, shear stress and sediment concentration profiles in smooth open channels; (2) experiments on bedload particle velocity in smooth and rough channels; (3) field measurements of sediment transport by size fractions in curved flumes. In terms of computer modeling, significant advances have been achieved in: (1) flashflood simulation with raster-based GIOS and radar precipitation data; and (2) physically-based computer modeling of sediment transport at the watershed scale with CASC2D-SED. Field applications, measurements and analysis of hydraulic geometry and sediment transport has been applied to: (1) gravel-bed transport measurements in a cobble-bed stream at Little Granite Creek, Wyoming; (2) sand and gravel transport by size fraction in the sharp meander bends of Fall River, Colorado; (3) changes in sand dune geometry and resistance to flow during major floods of the Rhine River in the Netherlands; (4) changes in hydraulic geometry of the Rio Grande downstream of Cochiti Dam, New Mexico; and (5) analysis of the influence of water temperature and the Coriolis force on flow velocity and sediment transport of the Lower Mississippi River in Louisiana. Recent developments also include two textbooks on "Erosion and Sedimentation" and "River Mechanics" by the author and state-of-the-art papers in the ASCE Journal of Hydraulic Engineering.

• Ocean and Polar Research
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• v.31 no.4
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• pp.283-296
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• 2009

Oceanographic survey data were analyzed to understand the characteristics of a warm eddy observed in the Ulleung Basin in July 2005. The temperature distribution at 200 db and vertical sections provided evidence of the warm eddy in the Ulleung Basin (UWE05). Based on the 5$^{\circ}C$ isothermal line on 200 db temperature, the major axis was 160 km from southwest to northeast, and the minor axis was 80 km from southeast to northwest. The homogeneous layer in the thermocline of UWE05 had mean values of 10.40$^{\circ}C$ potential temperature, 34.35 psu salinity, and 26.37 kg/m$^3$ potential density (${\sigma}_{\theta}$) and provided evidence that UWE05 also existed during the winter of 2004-2005. A warm streamer initially flowed along the circumference of UWE05 and mixed with the upper central water. Two northward current cores were found on the western side of the measured current section at the central latitude of UWE05. One was the East Korean Warm Current (EKWC) and the other was the main stream of the western part of UWE05. Geostrophic transport of the upper layer (from the surface to the isopycnal surface of 26.9 ${\sigma}_{\theta}$) was approximately 2.5 Sv in the eastern side of UWE05. However, the measured transport was twice as large as the geostrophic transport. Mass conservation of geostrophic transport was well satisfied in the upper layer. The direct current measurements and geostrophic transport analysis showed that the EKWC meandered around UWE05.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.50-55
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• 1999

Gao and Collins method (two-dimensional sediment transport trend-vector model) using grain-size parameters (mean grain size, sorting coefficient, and skewness) calculated by the statistical moment method is introduced to understand semi-quantitatively the sandy and surficial sediment transport trends on a coast of the East Sea. The result is the sediment transport vectors which indicate transport paths of surficial sediment by wave-induced currents. The corresponding morphological feature is a spit developed at the mouth of the Nam¬dae stream, which is a resultant sediment transported by longshore current and is blocking the circulation of ocean. After this, it is thought that seasonal research and hydrodynamic measurements are needed for verification of the results.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.278-280
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• 2007

In this paper, wd design the Program Specific Information (PSI) parser and its On-Screen Display (OSD) on the middleware of ALi M3330 MPEG-2 decoder processor to analyze DVB-T Transport Stream(TS) information. To test the functional operation of the designed parser, we implement the DVB-T test board including the RF-tuner using ALi M3330 MPEP-2 decoder processor and confirm the correct operation using the input TS stream generated by DVB-T stream generator. The developed PSI parser could be used for the test environment, various channel extension, and the development of DVB-T reception module.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.364-367
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• 2009

This paper presents a scheme that generates a caption file by extracting a Closed Caption stream from DTV signal. Note that Closed-Captioning service helps to bridge "digital divide" through extending broadcasting accessibility of a neglected class such as hearing-impaired person and foreigner. In Korea, DTV Closed Captioning standard was developed in June 2007, and Closed Captioning service should be supported by an enforcing law in all broadcasting services in 2008. In this paper, we describe the method of extracting a caption data from MPEG-2 Transport Stream of ATSC-based digital TV signal and generating a caption file (SAMI and SRT) using the extracted caption data and time information. Experimental results verify the feasibility of a generated caption file using a PC-based media player which is widely used in multimedia service.

• ETRI Journal
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• v.26 no.2
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• pp.112-121
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• 2004

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka-147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG-4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG-4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG-4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG-4 elementary-stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.17-22
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• 2010

In this paper, integral TS(Transport Stream) demultiplexer of a multi-modal receiver is proposed according to the multiple standards of European terrestrial digital broadcasting DVB-T(Digital Video Broadcasting Terrestrial), and mobile terrestrial digital broadcasting T-DMB(Terrestrial Digital Multimedia Broadcasting). This USB based integral receiver could recover the multi-modal broadcasting audios by memory sharing technique which was utilized to decrease the load by the control of streaming multi-modal broadcasting. As a result of performance analysis for a proposed integral TS demultiplexer, the CPU occupational efficiency of windows based integral demulitiplexing is improved compared with DVB-T, and T-DMB respectively.

• Water for future
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• v.21 no.3
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• pp.291-291
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• 1988

The two dimensional time dependent flow past a circular cylinder is analyzed numerically. In the analysis, equations of conservation of mass and momentum are transformed to equations of stream function-vorticity and vorticity transport, and nondimensionalized by nondimensional parameters representing flow characteristics, The resulting stream function-vorticity equstion and vorticity transport equation are solved by successive over relaxation scheme and alternating direct implicit scheme. Numerical experments are performed for the flow in the range of Reynolds number 125 to 275. The time dependent streamlines, vorticities, pressure on cylinder surface, separation angle, and drag and lift coefficients are calculated, and the method for estimation of pressure on cylinder surface and the outer boundary limit are developed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.6
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• pp.1163-1170
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• 1992

A computer program was developed to analyze the two-dimensional unsteady incompressible viscous flow behind a rectangular bluff body between two parallel plates. The Peaceman-Rachford alternating direction implicit numerical method and Wachspress parameter were adopted to solve the governing equations in vorticity-transport and stream function formulation. The steady state flow and the vortex flow behind a rectangular bluff body in a chemical were investigated for Reynolds numbers of 200 and 500. The vortex shedding was generated by a physical pertubation numerically imposed at the center of the flow field for a short time. It was observed that the perturbed flow became periodic after a transient period.